A passenger (R) has her temperature checked by a Centers for Disease Control (CDC) staff member at the entrance of Sungshan Airport in Taipei on April 4, 2013. Taiwan enhanced its level of alert against bird flu and set up a contingency centre after China's report of seven people infected with a new strain of avian influenza, including two deaths. AFP PHOTO / Sam Yeh (Photo credit should read SAM YEH/AFP/Getty Images) | SAM YEH via Getty Images

The flu victim was travelling with two others and began to feel unwell on a return flight from Beijing to Vancouver on Dec. 27 via Air Canada Flight 030. The person then flew to Edmonton on board Air Canada Flight 244 and was admitted to a hospital on Jan. 1.

The individual died two days later but Heath Canada is stressing the case is an "isolated" one, adding that the two others who travelled with the victim are under the watch of health-care workers.

Health officials have not identified the gender, age or other details about the victim.

Symptoms of the the type A avian influenza virus aren't different from the regular flu, with coughing, aching muscles and a sore throat the most common signs. They do take anywhere from two to eight days to manifest, with pneumonia or other respiratory conditions being the more serious symptoms.

Canada's National Advisory Committee on Immunization recommends that anyone over the age of six months who doesn't have a specific reason not to get a flu shot (previously having an allergic reaction to one) consider getting it. The average length of illness from the flu is seven days,which can be a major inconvenience for most people. And even healthy people can become quite ill.

There are some people who are at a higher risk for complications for the flu: people older than 65, pregnant women, children aged six months to two years, people with chronic diseases, and people who are otherwise immuno-compromised. The flu shot is especially important for these people, or those are in regular contact with a high-risk individual or group. People who live in nursing homes or chronic care facilities may also be more likely to be exposed to influenza, as are those who work with patients at high risk for contracting the disease.

Those with egg allergies should be able to receive the inactivate flu vaccine without issues, but it's not known if the nasal vaccine is same for them. The new advice this year is that those with an egg allergy should be okay to get the vaccine, but should be observed for potential reactions, said Dr. Roth. Anyone who has ever had a severe allergic reaction to a previous flu shot, or contracted GBS within six weeks of a previous influenza vaccination, should speak with their doctor before getting the vaccine again. Also, the shot isn't given to infants younger than six months of age. And if you currently have a fever, wait to get your shot until it's gone, Dr. Roth said.

The flu vaccine protects against the three strains of the flu that researchers believe will be most common for that flu season, Dr. Roth explains. The flu shot, in general, is 70 to 90 per cent effective in preventing the flu in healthy kids and adults when the strains it contains match those in circulation. The vaccine is less effective for the elderly, though it can reduce the severity of symptoms for those who do contract influenza.

Influenza is a respiratory infection caused by influenza A and B, and is usually contracted in late fall and winter. The flu is spread by direct contact and the droplets expelled when we cough, sneeze, breathe or talk. Symptoms of influenza include the sudden onset of headache, chills, cough, fever, lack of appetite, sore muscles, fatigue, sneezing, watery eyes, runny nose, and sore throat. In children, the flu can also cause nausea, diarrhea, and vomiting. There are many strains of influenza, and the virus is mutating constantly. Having had the flu once before doesn't protect you from getting it again, because you could simply contract a different strain.

Many people mistake a bad cold or other respiratory illness for the flu, but there is a difference. Influenza symptoms are generally more serious and include fever and muscle aches. Colds, caused by different bacteria or viruses, rarely result in serious illness, but it's possible to get pneumonia and other conditions as a result of the flu. Also, though we tend to refer to stomach illnesses as the stomach flu, they are not actually influenza instead, they are the result of other viruses or bacteria, or food-borne illnesses. The flu vaccine doesn't protect against colds or stomach viruses.

It's recommended that you get your vaccine as early as possible. It takes about two weeks after vaccination for your body to develop the antibodies that prevent you from getting the flu, so getting the needle at the start of the flu season is the best way to avoid illness. Immunity varies by person but research has shown that the protection from your annual vaccine will last throughout flu season, even if you get the shot early. That said, if you didn't get an early shot, it's still worth getting vaccinated later in the year or even early into the next; flu seasons tend to peak in January and February, outbreaks are unpredictable and can last well into the spring.

Though the flu can be miserable, you can also spread it without even realizing that you've been exposed. According to info from Harvard, 20 to 30 per cent of people carrying the influenza virus have no symptoms of the disease.

Herd immunity is the type of immunity that occurs when the vaccination of a significant percentage of a population provides protection against disease for those who are not or cannot be vaccinated or do not have immunity. Because most of a population have been vaccinated against a given disease, it's very difficult for that disease to spread because there are not many people who can actually become infected and pass it on. Getting vaccinated against the flu can help to work towards herd immunity and if the majority of members of a community are vaccinated against influenza, it will be harder for the disease to be contracted by those who cannot be vaccinated and don't have immunity. This is particularly important because it's often the case that those who can't be vaccinated are also at a higher risk of serious complications from the flu, for example, very young infants.

For most people, the flu vaccine is given in a single shot. However, children who are aged six months to nine years and are getting the vaccine for the first time should receive two doses, four weeks apart. The nasal spray vaccination is also available in Canada, with a prescription, though it is not recommended for pregnant women due to lack of testing in that group. And elderly patients can receive a shot with an adjuvant that boosts their immune response. Dr. Roth said.

Flu shots are free to all residents aged six months or older in Ontario and Alberta. In other provinces, some people are eligible for a free shot, and others will have to pay a small fee of $10 to $15.

Each year, the flu vaccine offers protection against the three strains of the virus that researchers believe will be the most common that cold and flu season. Flu tends to move west to east, Dr. Roth explained, so researchers watch for common strains in other parts of the world to predict what will show up here when our flu season hits. So the shot does not protect against all strains of flu, but does offer protection from the ones you are most likely to encounter. The vaccine changes annually, which is why it's important to get your shot each year.

In the vast majority of cases, the influenza vaccine causes only mild side effects, if any. The most common one is redness or soreness at the injection site. Some people get a headache or mild aches and tiredness if they get a vaccine that uses a modified live virus, like the nasal spray, or if they are getting the flu shot for the first time. In very rare cases, the flu can lead to Guillain-Barre syndrome, or GBS, which is a condition that leads to muscle weakness or paralysis. GBS is most common after infections, but may be associated with the flu in about one per million shot recipients. Recent research found that it's much more likely —thought still very rare — to get GBS from contracting the flu virus itself than from the flu vaccine.

Many people report getting the flu shortly after getting a flu vaccine, and believe that the latter caused the former. But the flu vaccine cannot give you the flu, "It's impossible," said Dr. Roth. Most vaccines use dead viruses, and dead viruses can't make you sick. The FluMist nasal vaccine uses a live virus, but it has be specially engineered to remove the parts of the virus that can make you ill. In a study that compared people who got the flu shot with those who received a control shot of salt water, the only difference in symptoms was redness and soreness at the injection site for those who got the real vaccine. The flu vaccine is generally given during a time of the year when people are more likely to get illnesses like colds and flus; if you come down with something shortly after getting your flu shot, it's nothing but coincidence.

It is safe to receive the inactivated flu vaccine in any stage of pregnancy. "When you get sick with influenza and you're pregnant, the outcomes are worse," said Dr. Roth. Women in the second half of their pregnancies are at higher risk of hospitalization due to influenza, as are those at any stage of pregnancy who have a chronic medical condition. And having the flu when you are pregnant is particularly miserable because many of the medications you could otherwise take to relieve your symptoms are off limits. The flu vaccine is also safe for mothers who are breastfeeding.

Thimersosal is a mercury-based preservative that has been the source of much controversy. It was previously used in some multi-dose vaccines, such as MMR, and a study by Dr. Andrew Wakefield linked it to autism. However, the study has since been fully retracted by the journal that published it, and its results have never been replicated by any other peer-reviewed medical research. There is no proof of a link between vaccines and autism. Single-dose flu vaccines do not contain thimerosal, whether they are given in the form of injection or nasal spray.

We think of the elderly and sick as those most at risk from the flu, and while they can have serious complications, healthy people are not immune to the disease's effects. In particular, children with no pre-existing health problems can become seriously — even fatally — ill because of influenza. "I don't think we've gotten the message out very well about how important [the shot] is for children," Dr. Roth said. "Even healthy kids can die of the plain old flu."

Though protection for H1N1, colloquially known as swine flu, used to be given in a separate shot, this year's influenza vaccine includes the strain. It's important to re-up your protection for this disease, which can be quite serious, each year as it's not yet known how long immunity from the shot protects you against it.

Right now the flu vaccine changes annually to include the strains thought to be most common that year, but researchers are working on a universal flu vaccine that would protect against a wider number of strains of the virus. In September, researchers discovered that people who managed to avoid serious illness from the H1N1 swine flu had more virus-killing CD8 T cells in their blood during the pandemic in 2009. That discovery indicated that a vaccine that stimulates production of those immune cells could offer a more wide-ranging influenza protection and got us one step closer to a universal vaccine.

Antivirals like Tamiflu are effective against influenza, especially if taken within the first 48 hours of your illness. However, antibiotics do nothing to treat the flu, antibiotics fight bacteria and influenza is a virus. They may, however, be effective if you get a bacterial infection as a flu complication; if your symptoms get worse over time, or just won't go away, get checked out. The idiom "feed a cold, starve a fever" is not true. In both cases, you need to stay hydrated, and though the flu may kill your appetite you should take in as much nutrition as you can manage.

Thorough and frequent hand-washing is your best defence against everyday illnesses like the flu. Here's a good rule of thumb: washing your hands for as long as it takes you to sing "Happy Birthday." Smoking makes people generally more susceptible to illness, so that's one more reason to quit (or not start). Covering your mouth with the crook of your elbow instead of your hands when you cough can help to prevent the transfer of germs. And if you are sick, stay home from work or school — you'll likely recover more easily if you rest, and you won't risk spreading it around.